add toolCallid and firstclass toolresult event #122

[IbrahimAhmed8]

Closes #122.

This PR addresses the issue with parallel tool calls by:

1. Adding toolCallId to the tool-call chunk variant in types.ts
2. Introducing a first class tool-result chunk variant
3. Updating the processEvent parser in client.ts to properly extract the tool call IDs and map incoming tool_result events to the new chunk type instead of falling back to the Unknown type
   and all tests n type checks are passing locally

[IbrahimAhmed8]

Closing this PR since the changes were merged via #144